The invention concerns a diesel pile hammer according to the pre-characterizing clause of claim 1.
In the case of such diesel pile hammers, the combustion fuel is injected, through an injection nozzle carried by the cylinder, into a fuel trough fashioned centrally in the piston-side end face of the striker. The opposing end face of the piston is graduated towards the edge, in steps, away from the striker. Fuel which is atomized when the piston impacts on the striker thus reaches the cylinder sliding surface. This portion of the fuel is to a large extent lost in respect of the actual combustion process.
The object of the present invention is to develop a diesel pile hammer according to the pre-characterizing clause of claim 1 so as to improve utilization of the fuel.
This object is achieved, according to the invention, by a diesel pile hammer according to claim 1.
In the case of the diesel pile hammer according to the invention, the piston circumferential surface extends essentially just as far in the axial direction towards the striker as the end face of the piston. This piston itself thus largely covers the cylinder sliding surface. The fuel which is atomized when the piston impacts on the striker reaches the piston end face, where it is available for the combustion process, and not the cylinder sliding surface.
Advantageous developments of the invention are disclosed by the sub-claims.
The development of the invention according to claim 1 is advantageous in further improving the availability for combustion of the fuel collected by the piston end face, since the annular trough in the piston end face, disclosed in claim 1, results in flows, as the piston end face approaches the striker end face, which distribute the fuel in the combustion air.
The development of the invention according to claim 2 results in a further improved covering of the cylinder sliding surface, by means of the striker.
If an annular trough is also provided in the striker end face, as disclosed in claim 3, fuel which has collected in the corresponding regions of the striker end face is supplied to combustion in a particularly effective manner due to air flows.
In the case of a diesel pile hammer according to claim 4, the annular troughs of the piston and striker together form an annular space in which there can develop annular air cylinders by which fuel collected in the corresponding end face regions is again supplied to the combustion air.
The geometry of the annular troughs disclosed in claim 5 is particularly advantageous for the development of toroidal flow cylinders.
The development of the invention according to claims 6 to 8 achieves the result that even portions of fuel which are essentially flung away, in the direction perpendicular to the cylinder axis, when the piston end face impacts on the striker end face, do not reach the cylinder sliding surface since they are arrested by the outermost end section of the striker circumferential wall (or, in the case of a projecting end face section of the striker, are analogously arrested by the piston circumferential wall).
The annular trough dimensions stated in claim 9 have proved, in particular, to be highly effective in respect of the fuel combustion.
The development of the invention according to claim 10 achieves the result that, when the piston end face impacts on the striker end face, the fuel can be suitably distributed in the angular and radial directions, the piston-side end face of the striker nevertheless being curved only to such a small extent, however, that fuel injected on to it remains there, without running off.
The development of the invention according to claim 11 likewise promotes the atomization of the fuel in the radial and circumferential directions, in a uniform manner.